Animals over Winter

How do habitats change? Temperature decreases As low as −50°C in the Arctic! Sometimes even colder! Hours of daylight decrease In some places it is dark for over four months! Increased rain and snowfall (especially in the northern hemisphere) How do habitats change in the winter? In temperate zones (i.e. anything between the tropics and the poles) temperatures decrease and there is less daylight. In the Arctic it can get as cold as minus 50 degrees Celsius and it is dark for over four months. There is also increased rain and snowfall, especially in the northern hemisphere. Food can much harder to find – the ground is often frozen or covered under a blanket of snow meaning resources can be scarce. This presents a challenge to many animal species. How will they adapt to deal with cold weather and decreased daylight and fewer food sources? Food supplies may be harder to find

American bison in summer habitat This picture shows American bison in summer: it’s a lush habitat, with lots of food and a warm climate. The American bison once roamed throughout North America, but commercial hunting and diseases transmitted by domestic cattle led to widespread declines, and today it occurs in only a few pockets of its former range. In Alberta, a stronghold for large free-roaming herds, the bison occupy the expansive prairies and open plains. In summer, some parts of Alberta can reach up to 40 degrees Celsius (104 degrees Fahrenheit).

American bison in winter http://www.arkive.org/american-bison/bison-bison/video-bi02.html American bison in winter This shows the American bison in winter. This video will show you more of the bison’s habitat in winter. [Play video: http://www.arkive.org/american-bison/bison-bison/video-bi02.html] As you can see, the conditions are severe: it’s cold, windy and dark. The bison struggle to eat and even to walk in the snow. In northern Alberta, temperatures are known to plummet to -54 degrees Celsius (-65 degrees Fahrenheit) during the winter months. Such changes in an animal’s habitat present major challenges to their survival, and many species have developed different ways to cope with the extreme conditions that winter in temperate regions can bring.

What do animals do in winter? Brrr – it’s cold! What do animals do in winter? What can animals do to deal with the harsh conditions, cold temperatures and increased darkness? Any ideas? [Ask the pupils to shout out their suggestions]

Animals can… Migrate Hibernate Stay in the area and: - Store food - Change their appearance - Change their behaviour There are many ways which animals can survive over winter, and because of the huge variation between species, different species will have different adaptations to cope with the changing environmental conditions. In general, animals can: Migrate - move from one region or area to another. Migration is usually seasonal, and the trigger for migration may be changes in the local climate, local availability of food, or for mating reasons. In winter, many species migrate from colder areas to warmer areas. Hibernate - enter a dormant, or sleep-like, state. Stay in the area and store food, change their appearance (grow a thick coat, for example) and change their physiology. Let’s look at each of these mechanisms in more detail after a quick exercise… Polar bear sleeping in the snow

Complete the worksheet STUDENT ACTIVITY: The left hand column shows various animals. The right hand column has some behaviours that these animals adopt over winter. Place an X in the box that corresponds with the correct behaviour and the correct animals. [Hand out the worksheet to the students and give them time to fill in their answers. Follow up with a class discussion about which type of overwintering behaviour each group of species employs and why. Can they think of any other species not listed which might use similar mechanisms to survive the winter?]

Answers!

Migration This means: to move from one region, country or climate to another In winter, migrating animals normally move from a colder climate to a warmer one One of the strategies animals can adopt to survive the cold, harsh winter is migration. This means: to move from one region, country or climate to another. In winter, migrating animals normally move from a colder climate to a warmer one. The first picture shows snow geese migrating. Birds often migrate in the V formation shown and there are two theories about why. One theory is that it helps them to communicate with each other. Another theory is that the geese take turns flying at the front of the V, so that the geese flying behind can conserve energy as they encounter less drag (in a similar way to cars in Formula 1). It seems most likely that both theories are correct: both communication and energy conservation are important. The second picture shows how important migratory behaviour is. Hand-reared birds are being taught to migrate by following a microlight aircraft, so that when they are adults they are able to utilise this behaviour which enables them to survive over winter. Snow geese migrating: flying in a ‘V’ formation Snow geese being taught to migrate by following a microlight aircraft

Snow goose: Migration case study Migrate to a warmer climate in winter Spend spring and summer in the Arctic (Alaska, Greenland, Canada) Fly south to a warmer climate in autumn Overwinter in Mexico and the Gulf Coast Some birds fly all the way in one flight! - 1,700 miles in 70 hours Snow geese spend the spring and summer in the Arctic: places like Alaska, Greenland and Canada. This is where they breed and rear their chicks. They then fly south to a warmer climate in autumn and spend the winter in Mexico and the Gulf Coast of the USA. Some birds fly all the way in one flight! They can fly continuously for over 70 hours and 1,700 miles. Snow geese migration video: This video from the BBC shows a flock of snow geese returning from their wintering grounds to the Arctic. http://www.bbc.co.uk/nature/adaptations/Animal_migration#p00381dc [Play video – 1 min 58 secs – play up to 1 min] Snow geese migrating

Monarch butterfly: Migration case study Longest known insect migration North American and Canada populations migrate southward to overwinter - Up to 3000 miles! - Cover 80 miles per day! Millions of individuals roost throughout winter in a state of relative inactivity Not all populations of the monarch butterfly migrate; however, in the North American and Canadian populations several short generations occur in summer, followed by the last summer generation which has a long lifespan. This generation migrates for up to 3000 miles and can cover 80 miles per day. Even though it is cold in their wintering grounds, it is still much warmer than Canada or northern America. However, it is a risky strategy, as you can see in this video from the BBC’s ‘Life’ series: http://www.bbc.co.uk/nature/adaptations/Animal_migration#p0053k5f The monarch butterflies are at risk from predators and the cold. Nonetheless, millions of monarch butterflies roost in these forests in a state of relative inactivity, which leads us nicely to…

Hibernation This means to go into a dormant (torpid) state over winter Sliding scale of hibernation: Some animals hibernate throughout winter Some animals wake up to feed Hibernation. The monarch butterfly both migrates and hibernates. Hibernation means to go into a dormant, or torpid, state over winter. There is a sliding scale of hibernation. Some animals hibernate throughout winter, whereas some wake up periodically to feed. This brown long-eared bat is hibernating. Brown long-eared bat hibernating

True hibernation Body temperature drops Metabolic rate slows Breathing and heart rate decreases Live off stored fat reserves Can lose up to 40% of body weight In true hibernation, body temperature drops and breathing and heart rate decrease. Metabolic rate slows so the animal doesn’t need to feed and they can live off stored fat reserves. Animals can lose up to 40% of their body weight and they are very hard to wake up. The picture shows a common dormouse hibernating. Common dormouse hibernating

True hibernator: Arctic ground squirrel Unique amongst mammal hibernators as their body temperature drops to -3ºC! Every few weeks they warm up slightly by shivering - Possibly to prevent brain damage Risky strategy: - Some Arctic ground squirrels never wake up The Arctic ground squirrel is a fantastic example of a true hibernator. Whilst hibernating its temperature drops to minus 3 degrees Celsius, which is the lowest of all mammals. Every few weeks they need to warm up slightly by shivering. This is thought to prevent brain damage from excess cold, but even when they warm up slightly, they still don’t wake up. Lowering body temperatures to minus 3 degrees Celsius is a better option for the Arctic squirrel than migrating or staying above ground in the freezing Arctic winter. However, it is still a risky strategy, as some Arctic ground squirrels never wake up! Arctic ground squirrel

True hibernator: painted turtle Spend winter hibernating at the bottom of a river bed Can hibernate for up to six months Use a ‘natural antifreeze’ to prevent their blood from freezing It’s not only mammals that hibernate. Reptiles such as the painted turtle also spend their winter in a sleep-like state. They normally hibernate in the bottom of a river bed and can stay there for up to six months. Painted turtles use a natural antifreeze to stop their blood from freezing, a lot like the antifreeze used in cars. The temperature in the surrounding environment can fall to as low as minus ten degrees Celsius, and ice crystals often form around the hibernating turtles, and even inside their bodies, but the antifreeze proteins in their tissues protect them from the harmful effects of freezing. [Play video: “Frozen turtles” from the BBC’s ‘Life in Cold Blood’: 3 mins 6 secs (play up to 2 mins 13 secs)] http://www.bbc.co.uk/nature/adaptations/Hibernation#p0060vdd Painted turtle

Partial hibernation Body temperature drops (but often not as low as true hibernators) Breathing and heart rate slow (but often not as slow as true hibernators) [Play video: “Siberian hibernation” from Realms of the Russian Bear” 1 min 58 secs] http://www.bbc.co.uk/nature/adaptations/Torpor#p00382fp The video shows two different hibernators. A marmot that only wakes up once every two weeks and a chipmunk that wakes up every four days to feed. In partial hibernation, body temperature drops, but often not as low as that of true hibernators. Breathing and heart rate slow, but often not as slow as true hibernators. Partial hibernators can be more easily woken than true hibernators, in case of danger. Brown bears can enter full or partial hibernation. When a female bear nurses her cubs, she still conserves energy by lowering her metabolic rate, but her temperature doesn’t drop as low as it would in full hibernation and she can eat, move around and feed her cubs. Brown bear: a full and partial hibernator Can be more easily woken than true hibernators (can wake up in case of danger) Awake to feed, drink and even walk around

Resident animals Animals which stay in the same area and change their behaviour or appearance rather than hibernating or migrating. Resident animals are animals which stay in the same area and change their behaviour or appearance rather than hibernating or migrating. These reindeer develop a layer of fat and a thick coat to protect against the cold. Reindeer in winter coat

What can resident animals do? Store food Change their diet Change their coat colour Grow a thicker coat Lay down a thick layer of fat Decrease their metabolic rate What can animals that stay in the same area do to adapt to the harsh conditions? They can: Store food, which is what squirrels do. In the autumn grey squirrels hoard food in small scrapes in the ground, which are then buried. Squirrels have a fantastic memory and remember where they hid their food. They also have a fantastic sense of smell, so once in the general area they can find the exact scrape by smell. Animals can change their diet in winter, for example the skunk. Most species that do this tend to be generalists, which can feed on a wide variety of different foods. Other species, such as the stoat, change their coat colour. A white coat helps them to be camouflaged against the snow. Some animals grow a thicker coat and lay down a thick layer of fat like the reindeer. Many animals can decrease their metabolic rate so that they do not need to feed as often. Skunks change their diet in winter

Arctic fox: Adaptations to the survive the winter These pictures show the Arctic fox in its thick, white winter coat and in its thinner, dark summer coat. Arctic fox in winter coat Arctic fox in summer coat

What about species that live in even colder places? We’ve talked about the different strategies that some animals that live in relatively cold climates over winter might adopt in order to survive. But what about animals that live in the polar regions, where it is cold all the time and where the conditions become even worse in winter? What kinds of adaptations do species that inhabit these harsh conditions have to survive? Think about behavioural adaptations, anatomical adaptations and physiological adaptations of these species. In most cases, it will be a combination of all three types of adaptation that make these animals so well adapted to survive in extreme environments. Discussion point: In order to assess students’ understanding about adaptations to cold environments, get them to think about how each of these animals (Emperor penguin, polar bear, crabeater seal, grey wolf) might be adapted to a) move through their habitats in winter and b) survive over winter in harsh conditions. The two following examples – emperor penguin and polar bear - are species that are already extremely well adapted to cold climates; however, their behaviour, for example, still changes from summer to winter: penguins huddle in large colonies to conserve warmth, while polar bears build dens that may be several metres deep to shelter from the icy wind.

Thick layer of fat (blubber) under the skin for insulation Thick skin Large body size (loses less heat) Cold feet! Adaptations to the Arctic & Antarctic environment Emperor penguins: Live in the Antarctic where it is extremely cold, and the water temperatures never rise above freezing. They live on pack ice (floats on the surface of the ocean) and in the oceans around Antarctica. They breed on the land or ice surfaces along the coast and on islands. In order to cope with these extreme conditions out of water, emperor penguins have thick skin, with a layer of thick fat, or blubber, under the surface of the skin which acts as insulation. During the winter when the males are guarding the eggs, all the birds within the colony huddle together to keep warm, with some colonies comprising several thousand penguins. The penguins rotate every now and then, so that those on the outside of the huddle get to move into the huddle so that none of the penguins are too cold for too long. The dark feathers of penguins absorb heat from the sun (although during the winter it is dark 24 hours a day), and the feathers are tightly packed together and overlap, providing waterproofing and warmth. Emperor penguins are also quite large and for almost all species, the larger the animal, the smaller the surface-area: volume ratio, and so the less relative area there is to lose heat. Penguins also have a number of interesting mechanisms to cope with standing on ice all day. Penguins lose heat through their feet (and flippers) and so to counteract this heat loss, the muscles that move a penguins feet aren’t found in the feet themselves and instead are located in a warmer part of the body, meaning that even if the feet get really cold they can still be operated normally. The blood to the feet is also carefully controlled: warm blood entering the feet flows past cold blood leaving the feet, cooling it down, while the cold blood leaving the feet is warmed up by the warm blood entering, warming it up again. This means that blood flow to and from the feet, where it is much colder, doesn’t affect the penguin’s core body temperature. If it gets really cold, penguins can reduce the contact they have with the ice even further by rocking on to their heels, using their tail for balance. Huddle together for warmth Tightly overlapping feathers for waterproofing and warmth

Large body size to minimise heat loss Black skin (retains heat) Light-coloured fur Large feet to spread weight on ice/snow Hollow fur to trap air for insulation Small ears and tail to reduce heat loss Polar bears: Live in the Arctic and are the largest land carnivores (eat meat). They have white or light-coloured fur which helps the polar bear to camouflage itself against the ice and snow. The fur is also very thick, while under the skin there is a thick layer of fat (which can be up to 11cm thick) for insulation against the cold. The skin of the polar bear is actually black, which aids heat retention (stops heat being lost from the body). With such good insulation, the polar bear actually risks overheating. To prevent this, the polar bear usually moves slowly and rests often, and excess heat is released where fur is absent or where the blood vessels are close to the skin (e.g. around the muzzle, nose, ears, feet, shoulders). The polar bear will often swim on warm days or after physical activity in order to cool down. The polar bear has a small surface area to volume ratio to minimise heat loss, and long, stiff hairs between the pads on the bear’s feet protect them from the cold and provide traction (grip) on the ice. Compact ears and a small tail also help prevent heat loss. Large feet help spread the weight of the polar bear more evenly to prevent it from breaking the ice or sinking into the snow. The fur of the polar bear is also hollow and traps air inside, providing an extra later of insulation and aiding buoyancy when swimming. On very cold days, polar bears dig shelters in snow banks and curl up in a tight ball. Sometimes they cover their muzzles, which radiate heat, with their thickly furred paws. Polar bears are able to enter a state of waking hibernation, in which the bear maintains a normal body temperature but is able to save energy by reducing its metabolic rate and recycling certain proteins. Thick layer of fat under the skin Stiff hairs on feet to protect from the cold and provide grip ‘Waking hibernation’

Let’s move on to the activity… Any Questions? Activity: Have students pick one of the species (not polar bears or penguins) mentioned in this presentation (see list on final slide). Using ARKive (www.arkive.org) and other internet resources, have students work individually, in pairs, or in small groups to research their species, identifying its typical habitat, how its habitat differs between summer and winter, and any adaptations the species has to help it survive overwinter (e.g. migration, hibernation, change in behaviour or physiology). Using their research, have students create a poster or PowerPoint presentation about their species and its adaptations to winter. Let’s move on to the activity…

Activity Choose one of the species from the list. Make a poster about your species. What is it called? Where does it live? Using the ARKive website and other websites, find out about the different adaptations your species has to survive winter. Draw a picture and explain the different adaptations your species has to survive… Does it migrate? Does it hibernate? Does it grow a thick coat? Does it store food?

Species to choose from Bar-headed goose Grey squirrel American bison Stoat Arctic tern Dormouse Garter snake Blue whale Arctic fox Skunk Brown bear Swallow